1. Field of the Invention
The invention relates to a radiation-sensitive resin composition, a polymer, a compound, and a method for producing a compound.
2. Discussion of the Background
In the field of microfabrication such as production of integrated circuit devices, a fine resist pattern may be formed by forming a resist film on a substrate using a radiation-sensitive resin composition that includes an acid-labile group-containing polymer, exposing the resist film by applying short-wavelength radiation (e.g., excimer laser light) to the resist film via a mask pattern, and removing the exposed area using an alkaline developer. The above process may utilize a radiation-sensitive resin composition that includes a photoacid generator that generates an acid upon irradiation, and exhibits improved sensitivity due to the acid.
When using such a radiation-sensitive resin composition, post-exposure bake (PEB) may be performed in order to promote dissociation of the acid-labile group, and ensure that the exposed area exhibits sufficient solubility in an alkaline developer. The PEB temperature is normally set to about 90 to 180° C. However, while dissociation of the acid-labile group sufficiently occur when using such a PEB temperature, diffusion of an acid into the unexposed area may occur significantly, and affect the pattern-forming capability of the radiation-sensitive resin composition. In particular, since the line width of the resist pattern was been reduced to 90 nm or less, it may be difficult to obtain a resist pattern that has a good pattern shape, and has small line width roughness (LWR) (i.e., an index that indicates a variation in line width).
The above problem may be solved by suppressing the acid diffusion speed by reducing the PEB temperature. In recent years, it has been desired to reduce energy consumption during the production process by reducing the PEB temperature from the viewpoint of reducing the environmental impact and the production cost.
However, when the PEB temperature is reduced, the dissociation rate of the acid-labile group may decrease, and the resist film in the exposed area may not be sufficiently dissolved. As a result, the pattern-forming capability of the radiation-sensitive resin composition may deteriorate. Therefore, a technique has been studied that makes it possible to reduce the PEB temperature by designing an acid-labile group that easily undergoes dissociation. For example, a positive-tone photosensitive resin composition that includes a resin that includes an acid-labile group having a specific acetal structure (see Japanese Patent Application Publication (KOKAI) No. 2008-304902), and a positive-tone resist composition that includes a resin that includes a structural unit including a tertiary ester structure and a structural unit including a hydroxyalkyl group (see Japanese Patent Application Publication (KOKAI) No. 2009-276607), have been proposed.